The purpose of my project is to investigate the structure-activity and conformation-activity relationships of opiates which may have multiple conformations available to them due to rotations about single bonds. The energies of stable conformations of these molecules will be computed using potential energy functions, and correlations will be attempted to their pharmacological activities. In addition, the geometries of the various conformations will be examined and related to those of rigid opiates and the enkephalins which are believed to be the endogenous equivalent of opiates. This should allow us to determine the biologically significant conformations of flexible opiates and will test a number of hypotheses which have been suggested as to their conformational requirements. In addition, detailed comparisons will be made between our conformational data and those from other sources such as X-ray crystallography and nuclear magnetic resonance. This will insure that our results continue to be physically realistic and will allow further testing of our method of conformational analysis. Efforts will also be made to make theoretical predictions that can be experimentally verified.